Glucose-6-phosphatase
| Glucose-6-phosphatase | ||
|---|---|---|
| Mass / length primary structure | 357 amino acids | |
| Isoforms | G6Pase, G6Pase-2, G6Pase-3 | |
| Identifier | ||
| Gene name (s) | G6PC , G6PC2 , G6PC3 | |
| External IDs | ||
| Enzyme classification | ||
| EC, category | 3.1.3.9 , phosphatase | |
| Response type | Hydrolysis of a phosphoric acid ester bond | |
| Substrate | D-glucose-6-phosphate + H 2 O | |
| Products | D-glucose + phosphate | |
| Occurrence | ||
| Homology family | G6Pase | |
| Parent taxon | Euteleostomi | |
Glucose-6-phosphatase (abbr .: G6Pase , gene : G6PC ) is the name of the enzyme that catalyzes the cleavage of phosphate from glucose-6-phosphate (G6P) . This reaction is an indispensable part of several energy metabolic pathways in vertebrates . In humans, three isoforms of the enzyme are produced, which are encoded by the genes G6PC , G6PC2 and G6PC3 ; the corresponding enzymes are called G6Pase, G6Pase-2 and G6Pase-3. G6Pase is found in humans in the liver , kidneys and, in small amounts, in the intestine , G6Pase-2 is specifically localized in islet cells , and the enzyme activity of G6Pase-3 is doubtful. Mutations in G6PC are responsible for von Gierke disease type Ia, and variations in G6PC2 are associated with high glucose levels during fasting (FGQTL1,> 5.55 mmol / L glucose ), a risk factor for diabetes mellitus ; Finally, deficiency in G6PC-3 can lead to severe familial neutropenia type 4 (SCN4).
The G6Pases are membrane proteins in the endoplasmic reticulum (ER), which together with glucose-6-phosphate translocase form a protein complex . This complex simultaneously ensures the flow of G6P into the interior (lumen) of the ER, and the hydrolysis of G6P to glucose and phosphate. Ultimately, the glucose is transported out of the ER, but the exact mechanism is still unknown (2008).
Catalyzed reaction
+ H 2 O + P i 
G6P is hydrolyzed to glucose. The reaction is practically irreversible.
The reaction is part of gluconeogenesis .
Individual evidence
- ↑ a b UniProt P35575 , UniProt Q9NQR9 , UniProt Q9BUM1
- ↑ D'Eustachio / Harris / reactome.org: Efflux of glucose from the endoplasmic reticulum
- ↑ Harris / reactome.org: alpha-D-glucose 6-phosphate + H2O ⇒ alpha-D-glucose + orthophosphate .
literature
- RM Cohn, RH Herman, D. Zakim: Glucose 6-phosphatase: a multifunctional enzyme . In: Am. J. Clin. Nutr. . 22, No. 9, September 1969, pp. 1204-10. PMID 4309941 .
